|SANTOS, ALEXANDRA - King College|
|BARBOSA-MORAIS, NUNO - New University Of Lisbon|
|RAMASWAMY, SNEHA - King'S College|
|HEMMINGS, OLIVER - King'S College|
|KWOK, MATTHEW - King'S College|
|O'ROURKE, COLLIN - Benaroya Institute|
|BAHNSON, HENRY - Benaroya Institute|
|JAMES, LOUISA - Queen Mary University Of London|
|GOULD, HANNAH - King'S College|
|SUTTON, BRIAN - King'S College|
|LACK, GIDEON - King'S College|
Submitted to: Allergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2020
Publication Date: 2/20/2020
Citation: Santos, A.F., Barbosa-Morais, N.L., Hurlburt, B.K., Ramaswamy, S., Hemmings, O., Kwok, M., O'Rourke, C., Bahnson, H.T., Cheng, H., James, L., Gould, H.J., Sutton, B.J., Maleki, S.J., Lack, G. 2020. IgE to epitopes of Ara h 2 enhance the diagnostic accuracy of Ara h 2-specific IgE. Allergy. 75(9):2309-2318. https://doi.org/10.1111/all.14301.
Interpretive Summary: Food allergy is an increasing problem worldwide. currently the only true diagnostic test for allergy is oral food challenge which is dangerous. the work described here uses peptide micro-arrays to identify allergen peptide that appear to be diagnostic of allergy and may be used in the future to replace food challenges.
Technical Abstract: Background: Understanding the discrepancy between IgE sensitization and allergic reactions to peanut could facilitate diagnosis and lead to novel means of treating peanut allergy. Objective: To identify IgE and IgG4 epitopes in peanut allergens and test their role in mast cell activation in peanut allergic (PA) and peanut sensitized but tolerant (PS) children. Methods: Synthetic overlapping 15-mer peptides of peanut allergens offset by 5 amino acids were spotted onto microarray slides by JPT Peptide Technologies. Plasma samples were tested for IgE and IgG4 binding to the peptides using immunofluorescence. Generated data files for 89 patients (including 53 PA and 27 PS) were analyzed with Bioconductor packages in R. The ability of peanut peptides to modulate allergen-induced effector cell activation was validated using a mast cell activation test. Results: IgE binding to two peptides of Arah1, four peptides of Arah2 and one peptide of Arah3 was greater in PA compared to PS patients as measured by log2-fold changes of foreground-to-background of fluorescence (B>0). These peptides were located on the surface of peanut allergens in structurally disordered or partially disordered loop regions. Pre-incubation with the Arah1 and Arah2 peptides reduced allergen-induced activation of mast cells (p<0001). IgE binding to one peptide on Arah5 and IgG4 binding to one Arah9 peptide was greater in PS than in PA patients. Conclusions: Epitopes located on the surface of peanut major allergens were differentially bound by IgE of PA and PS patients. Particular epitopes from Arah1 and Arah2 were important for allergen-induced effector cell activation.